Linking Cross Bar Controller

1. A crossbar comprising: N ports, each one of said N ports comprising: a link logic unit to receive messages and inbound data from a respective device, N- 1 output buffers corresponding respectively to others of said N ports; and a port arbiter to select one of said N- 1 output buffers to output outbound data to the respective device, wherein the inbound data is selectively transferred to the corresponding output buffer of a selected one of said others of said N ports.

2. A crossbar according to claim 1 , wherein said link logic unit determines a type of message from the respective device.

3. A crossbar according to claim 2 , wherein if the type of message is a local link message, a port function is performed and the message is not transferred.

4. A crossbar according to claim 2 , wherein if the type of message is a switch link message, the message and the inbound data are transferred.

5. A crossbar according to claim 1 , wherein said device comprises one of a switch and a second crossbar.

6. A crossbar according to claim 5 , wherein said N- 1 output buffers comprises a device table register to store a device number if the device comprises the switch.

7. A crossbar according to claim 5 , wherein said N- 1 output buffers comprises a device table register to store device numbers of devices connected to the second crossbar.

8. A crossbar according to claim 1 , wherein if the respective device is unable to receive outbound data, the respective device provides a message to said link logic unit, and wherein said link logic unit signals said arbiter to inhibit communication to the respective device.

9. A crossbar according to claim 1 , wherein if an nth one of said N- 1 output buffers is at least a predetermined capacity, a signal is sent to the nth one of said port arbiter of the other one of said N- 1 ports to inhibit further transmission.

10. A crossbar according to claim 1 , wherein said link logic unit determines a message type of one of said messages.

11. A crossbar according to claim 10 , wherein if said message type is a switch link message, said one of said messages and said inbound data are transferred to said selected one of said others of said N ports.

12. A crossbar according to claim 11 , wherein if said message type is a local link message, a port function is performed and said one of said messages and said inbound data not transferred.

13. A system comprising a crossbar according to claim 1 and said respective device of one of said N ports, wherein said respective device comprises one of a switch and a second crossbar.

14. A crossbar according to claim 13 , wherein said N- 1 output buffers of said one of said N ports each comprises a device table register.

15. A crossbar according to claim 14 , wherein said device table registers each store device numbers of devices connected to said respective device when said respective device comprises said second crossbar.

16. A crossbar according to claim 15 , wherein said device table registers each store a device number of said respective device when said respective device comprises said switch.

17. A system comprising a crossbar according to claim 1 and said respective device of one of said N ports, wherein if said respective device is unable to receive data, said respective device generates a message, and wherein said link logic unit of said one of said N ports sends a signal to said port arbiter of said one of said N ports to inhibit communication to said respective device based on said message.

18. A crossbar according to claim 1 , wherein if a kth one of said N- 1 output buffers of one of said N ports is filled to at least a predetermined level, a signal is sent to said port arbiter of the kth one of said others of said N ports to inhibit transmission to said one of said N ports.

19. A crossbar comprising: N port means, each one of said N port means comprising: link logic means for receiving messages and inbound data from a respective device, N- 1 output buffer means corresponding respectively to others of said N port means; and port arbiter means for selecting one of said N- 1 output buffer means for outputting outbound data to the respective device, wherein the inbound data is selectively transferred to the corresponding output buffer means of a selected one of said others of said N port means.

20. A crossbar according to claim 19 , wherein said link logic means determines a type of message from the respective device.

21. A crossbar according to claim 20 , wherein if the type of message is a local link message, a port function is performed and the message is not transferred.

22. A crossbar according to claim 20 , wherein if the type of message is a switch link message, the message and the inbound data are transferred.

23. A crossbar according to claim 19 , wherein said device comprises one of a switch and a second crossbar.

24. A crossbar according to claim 23 , wherein said N- 1 output buffer means comprises a device table register means for storing a device number if the device comprises the switch.

25. A crossbar according to claim 23 , wherein said N- 1 output buffer means comprises a device table register means for storing device numbers of devices connected to the second crossbar.

26. A crossbar according to claim 19 , wherein if the respective device is unable to receive outbound data, the respective device provides a message to said link logic means, and wherein said link logic means signals said arbiter means to inhibit communication to the respective device.

27. A crossbar according to claim 19 , wherein if an nth one of said N- 1 output buffer means is at least a predetermined capacity, a signal is sent to the nth one of said port arbiter means of the other one of said N- 1 port means to inhibit further transmission.

28. A crossbar according to claim 19 , wherein said link logic means determines a message type of one of said messages.

29. A crossbar according to claim 28 , wherein if said message type is a switch link message, said one of said messages and said inbound data are transferred to said selected one of said others of said N port means.

30. A crossbar according to claim 29 , wherein if said message type is a local link message, a port function is performed and said one of said messages and said inbound data are not transferred.

31. A system comprising a crossbar according to claim 19 and said respective device of one of said N port means, wherein said respective device comprises one of a switch and a second crossbar.

32. A crossbar according to claim 31 , wherein said N- 1 output buffer means of said one of said N port means each comprises a device table register.

33. A crossbar according to claim 32 , wherein said device table registers each store device numbers of devices connected to said respective device when said respective device comprises said second crossbar.

34. A crossbar according to claim 33 , wherein said device table registers each store a device number of said respective device when said respective device comprises said switch.

35. A system comprising a crossbar according to claim 19 and said respective device of one of said N port means, wherein if said respective device is unable to receive data, said respective device generates a message, and wherein said link logic means of said one of said N port means sends a signal to said port arbiter means of said one of said N port means to inhibit communication to said respective device based on said message.

36. A crossbar according to claim 19 , wherein if a kth one of said N- 1 output buffer means of one of said N port means is filled to at least a predetermined level, a signal is sent to said port arbiter means of the kth one of said others of said N port means to inhibit transmission to said one of said N port means.